The objective of this multicenter clinical trial is to develop interventions to prevent the development of NIDDM in people with a history of gestational diabetes (GDM) and impaired glucose tolerance (IGT) (Cohort I primary prevention) and the worsening of glucose tolerance in people with newly diagnosed NIDDM with an FPG less than 140 mg/dl (Cohort II, secondary prevention). The central hypothesis of this application is that improvement of insulin resistance will delay the onset of NIDDM in individuals at risk. Therefore, we propose a five year randomized non-pharmacological and pharmacological factorial treatment design aimed to improve insulin resistance: Stratification will assure an overall trial representation of Black (0.4), Hispanic (0.2), Native American (0.2), GDM (0.2) and other races including Caucasian (1.0) Power calculations indicate that 20 centers contributing with 200 patients each will be necessary to fulfill the goal of the study. We will recruit the study subjects from among the Thomas Jefferson University employees. From a preliminary survey of the 7,294 full-time employees with a response rate of 58% revealed that 52% of the employees are at risk for NIDDM and that 76% have indicated interest in a NIDDM prevention trial, if available. It is hoped that the screening treatment follow-up and outcome measures methods will be translated to the society at large. To this end, it is important that both community and work-site models be developed.